David Alan Pyke (1921–2001) is renowned for his study of identical twins, one of which had diabetes, in the early 1960s. The study was the largest of its kind in the world, and helped clarify the distinction between type 1 and type 2 diabetes. Pyke also helped to improve the outcome of diabetic pregnancies, and between the 1960s and 1980s fetal mortality declined from around 15 to around 5 per cent. Pyke received medical training at Cambridge University and University College Hospital, London. He was later appointed consultant physician to the diabetic department at King's College Hospital, London, and become head in 1970. He later attended the Queen Victoria Hospital in East Grinstead where he conducted a general medical outpatient clinic twice a week and was widely respected by the local general practitioners.